Emergency locking retractor for seat belts

ABSTRACT

An emergency locking retractor for seat belts comprises a spindle, a swing member loosely inserted into the spindle and having engaging teeth on the outer periphery thereof, a locking member having internal teeth engageable with the engaging teeth of the swing member, a synchrogear slidably rotatable with the spindle to engage the swing member with the locking member, and an acceleration sensing device engagable with the synchrogear. The swing member has a supporting tooth in addition to the engaging teeth, the synchrogear is provided with a balance weight for compensating deviation of the center of weight of the swing member from the rotation center of the spindle, and the spindle is provided with a reinforcing plate and further with projections integrally formed which are so positioned that the projected portions may be present on the upper surface of the swing member to prevent any upward movement of the swing member causing disengagement. The emergency locking retractor for seat belts is lightweight and simple in structure and has a locking mechanism operable with certainty in case of an emergency under any circumstance, thus being highly reliable.

TECHNICAL FIELD

This invention relates to an emergency locking retractor for seat belts.This retractor has an improved cam mechanism which acts as a swingmember. More particularly, this invention relates to a lightweight,highly reliable emergency locking retractor for seat belts which has aswing member provided with an inertial means for locking. The retractoris simple in structure and can operate with certainty.

DESCRIPTION OF THE BACKGROUND ART

A variety of retractors for seat belts have heretofore been proposed andput into practice. In recent years, emergency locking retractors (ELR)for seat belts have also been proposed. These emergency lockingretractors are provided with a mechanism capable of locking a seat beltin case of emergency, e.g. when acceleration exceeds a threshold value.On the other hand, a number of reseaches and developments have been madein automobile industries for fuel economization, enhancement of runningperformance and keeping of a large interior space. For these studies,individual automobile parts are requested to be lightweight and compact.

Under such circumstances, emergency locking retractors for seat beltsare also requested to be lightweight and compact so that a part of themetal parts used heretofore has been substituted with parts made of asynthetic resin to lighten the weight. For example, a metallic windingreel was made lightweight by a method wherein the reel was formed with asynthetic resin and the center of the reel was provided with a metallicreinforcing element. In recent years, emergency locking retractors forseat belts, which are compact as a whole and have a small number ofparts have been developed and actually put into practice wherein aspindle having rectangular ends is used to swing a swing member mountedloosely outside the spindle and the swing member is engaged and lockedwith a locking means fixed to a housing. Emergency locking retractorshaving such structure are disclosed, for example, in Japanese Laid-openPatent Appln. No. Sho. 57-128170 (U.S. Pat. No. 4,508,289) and JapaneseLaid-open Patent Appln. No. 58-94865 (U.S. Pat. No. 4,453,681).

However, the prior art emergency locking retractors disclosed in thesepublications are very complicated because the shape of a hole used inthe swing member for loosely inserting the spindle must be precise asthe swing of the swing member is controlled by such a complicated shape,thus making the manufacture of the emergency locking retractorstroublesome and the function thereof less reliable. When the swingmember is engaged with the locking member in these prior art retractors,the teeth of these members sometimes abut against each other at the topthereof and are not correctly engaged with each other. Under suchcondition, disengagement occurs when a strong force is exerted to awebbing, with the result that the webbing may significantly be pulledout and the emergency locking retractor function is then lost.

In the emergency locking mechanism of this type, the swing member mustalso be considered as a part of the inertial means. In these retractorswherein no consideration is paid to this problem, however, the center ofgravity of the inertial means does not correspond to the rotation centerof a webbing-winding shaft so that sensitivity of inertial locking mayvary according to the location of the shaft in rotation, thusinfluencing the stability of performance. Further, the load capacity ofthese retractors varies according to whether the position of the longeredges of the spindle of the webbing-winding shaft are located parallelor vertical to the direction of load. When the longer edges are locatedin a position which is vertical to the direction of load, the bendingstrength of the spindle itself is weakened as well so that the lockingmember and the swing member may be disengaged by deformation such astwisting of a resinous portion in the winding shaft or wherein the loadcapacity is considerably reduced. In the retractors disclosed inJapanese Laid-open Patent Appln. No. Sho. 58-94865, the rotation of thewinding shaft is restrained so that the swing member may be moved upwardfrom the fixed position for engagement such that the danger ofdisengagement may result. Further, the shape and structure of a hole foraccepting the spindle are too complicate for controlling the swingmember so that the manufacture of the retractor is made troublesome andsome problem arises in reliability of the function, as described above.

Even if the prior art emergency locking retractors for seat belts aremade lightweight by the use of parts made of a synthetic resin, however,there is still room for improvement by avoiding the necessity for highprecision in their manufacture, stabilizing inertial locking, byenhancing load capacity in the locking member and by simplifying thestructure. Thus, there is a demand for developing a new emergencylocking retractor for seat belts which overcomes these drawbacks.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide anemergency locking retractor for seat belts which, in case of emergency,is capable of always being reliably engaged with the locking memberregardless of the condition of the swing member to the locking member,so as to restrain the seat occupant effectively.

It is another object of the present invention to provide a highlyreliable emergency locking retractor for seat belts which is preventedfrom any disengagement of the locking member, improved in load capacityand stabilized in inertial locking sensitivity.

It is still another object of the present invention to provide anemergency locking retractor for seat belts which has a lightweight,compact size and is simple in structure.

It is a further object of the present invention to provide an emergencylocking retractor for seat belts which is easy and economical tomanufacture.

Other objects, features, and advantages of the emergency lockingretractor of this invention for seat belts will become more fullyapparent from the following description.

DISCLOSURE OF THE INVENTION

According to the present invention, there is provided an emergencylocking retractor for seat belts which comprises a housing, a windingshaft, a spindle having generally rectangular ends and integrallyprovided with the winding shaft, a swing member having engaging teeth onthe outer periphery thereof through which the spindle has been insertedloosely, a locking member fixed to the housing and having internal teethengageable with the engaging teeth and a supporting tooth of the swingmember, a synchrogear frictionally movable with the spindle androtatable against the spindle to engage the supporting tooth of theswing member with the internal teeth of the locking member, and anacceleration sensing device provided engageably with the external teethof the synchrogear, characterized in that the swing member has engagingteeth on the outer periphery of one end in the direction of the longeredges of the spindle and a supporting tooth on the outer periphery ofone end in the direction of the shorter edges of the spindle and iscapable of freely swinging against the spindle in the direction of thelonger edges thereof and also capable of swinging in the direction ofthe shorter edges thereof by rotating against the spindle, the engagingteeth and the supporting tooth being biassed at all times in thedirection of disengaging from the locking member by a spring means, thatthe synchrogear has been fixed with a balance weight to compensatedeviation of the center of gravity of the swing member to the rotationcenter of the winding shaft, that the spindle forms a pair ofprojections in the direction of its longer edges which are alwayspositioned above the surface of the swing member, and that the windingshaft is provided on the side of the locking member with a reinforcingplate.

The emergency locking retractor of the present invention for seat beltshas various features as compared with similar prior art products. One ofthe features resides in the structure of the swing member; it has asupporting tooth for assuring engagement of its engaging teeth with theinternal teeth of the locking member. Another feature resides in thestructure of the synchrogear, especially in fixation of a balance weightwhich makes the center of gravity of the swing member as a part of theinertial means to correspond with the center of the rotation axis of thewinding shaft thereby stabilizing the sensitivity of inertial locking.Still another feature resides in the structure of the spindle wherein apair of projections formed in the direction of the longer edges preventsdisengagement of the swing member by its upward movement.

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus are not limitativeof the present invention, and wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of an example of the emergencylocking retractor of the present invention for seat belt, showing thecharacteristic construction of this invention together with a part of awebbing;

FIG. 2 is a side sectional view showing the main part of the emergencylocking retractor for seat belts shown in FIG. 1;

FIG. 3 is a vertical sectional view showing the main part of theemergency locking retractor for seat belts shown in FIG. 1;

FIGS. 4-7 are illustrative drawings showing the process of operation ofthe emergency locking retractor for seat belts shown in FIG. 1;

FIG. 8 is a side sectional view showing another example of the emergencylocking retractor of this invention for seat belts; and

FIG. 9 is an illustrative drawing showing the locked state of theemergency locking retractor for seat belts shown in FIG. 8.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be explained in more detail withreference to the attached drawings. In all the drawings, the samereference numeral refers to the same part.

In an example of the emergency locking retractor (which may beabbreviated as ELR) of the present invention shown in FIGS. 1-3, ahousing 1 is constructed by a bottom plate 2 and side plates 3,3'disposed vertically on both edges of the bottom plate 2. Between theseside plates 3,3' is bridged a webbing-winding shaft 4 which is providedon one end thereof with an emergency locking mechanism and on the otherend thereof with a spring means 29 which imparts a webbing-winding forceto the winding shaft 4. This spring means 29 is mounted to a cover 30functioning also as a support therefor. In a hole in the central portionof the side plates 3 and 3' the winding shaft 4 is inserted. Thiswinding shaft 4 is shown by a surrounding chain line and is constructedby a guide drum 4', a spindle case 4", a spindle 7 and a reinforcingplate 8'. The spindle case 4" is inserted into the guide drum 4' whilethe reinforcing plate 8' is disposed in a recess formed in one end ofthe spindle case 4" and also disposed in the spindle 7. In response tothe demand for lightening the weight, it is advantageous to manufacturethe spindle case 4" with a synthetic resin. The spindle 7 is insertedinto the spindle case 4" through a hollow hole of a rectangular shape incross section formed in the central portion of the spindle case 4". Thespindle 7 extends outwardly at both ends from the spindle case 4" and isin a rectangular shape as a whole. As this spindle 7 is generally of arectangular shape, it can be considered to have a longer side and ashorter side. Further, when viewed from an end of the spindle 7, thisspindle may be considered to have a generally rectangular shape with twoopposing edges which are longer than the remaining two opposing edges.The end of the spindle for the locking mechanism forms a pair ofprojections 8. The reinforcing plate 8' is positioned at around theportion where the spindle case 4' is supported by the side plate 3. Alocking member 5 has internal teeth 6 on the inner periphery thereof andis fixed to the side plate 3 of the housing 1. A swing member 9 isloosely inserted through an insertion hole 13 into the spindle 7. Inthis swing member 9, engaging teeth 10 engageable with the internalteeth 6 of the locking member 5 are formed on the outer periphery of oneend of the swing member 9 and are located in the direction of the longeredges in which the spindle 7 extend. Also, a supporting tooth 11engageable also with the internal teeth 6 of the locking member 5 isformed on the outer periphery of one end of the swing member 9 and thistooth 11 is located in the direction in which the shorter edges of thespindle 7 extend. Further, an extended portion 12 is formed on the outerperiphery of the swing member 9 adjacent to the engaging teeth 10.

The insertion hole 13 is elongated in the direction in which the longeredges of the spindle 7 extend and is enlarged at the side opposite theteeth 10 and opposite the supporting tooth 11 so that the swing memberis capable of swinging against the spindle 7 in the direction of thelonger edges thereof and also capable of swinging in the direction ofthe shorter edges thereof while engaging the edge of the insertion hole13 when the spindle 7 is rotated against the swinging member 9. By therotation of the spindle 7 against the swing member 9 in thecounterclockwise direction as seen in the drawings, the projections 8act to engage the insertion hole 13 whereby the swinging member 9 swingsin the direction of the shorter edges of the spindle 7 to permitengagement of the supporting tooth 11 with the internal teeth 6. Theswinging member 9 then swings in the direction of the longer edges ofthe spindle 7 to permit engagement of the engaging teeth 10 with theinternal teeth 6. The engaging teeth 10 and the supporting tooth 11 arenormally biassed always in the direction of disengagement with theinternal teeth 6. The swing member 9 has on its side surface aprojection 14 which is positioned in the neighborhood of the supportingtooth 11. A synchrogear 15 is mounted in such manner that it isfrictionally movable with the spindle 7 and has external teeth 16 on theouter periphery thereof. In the synchrogear 15, a control hole 17 isformed into which the projections 8 of the spindle are inserted torestrict the movable range of the synchrogear 15 relative to the spindle7. The synchrogear 15 is bored to form a guide hole 18 into which theprojection 14 of the swing member 9 is inserted. This guide hole 18 issomewhat longer in the radial direction of the synchrogear 15 so thatthe projection 14 of the swing member can slidably move along the guidehole 18 to permit engagement or disengagement of the supporting tooth 11with or from the internal teeth 6. A metal balance weight 19 is fixed tothe synchrogear 15 in a position rear to the guide hole 18 in thedirection of pulling out the webbing. A stopper 20 is fixed so as torotate together with the spindle 7 and has on a part of the outerperiphery thereof a projection 21 extending from the side. A springmeans 22 extends between the projection 21 and the projection 14 of theswing member 9 to energize the swing member 9 so that the engaging teeth10 and the supporting tooth 11 may be in a disengaged position from theinternal teeth 6 of the locking member 5.

On the outside of the synchrogear 15, an acceleration sensing device 23is provided adjacent to the external teeth 16. This acceleration sensingdevice 23 comprises a casing 24 constructed by a casing cover 24' and abottom plate 24", a pendulum 25 placed inside the casing 24 and a swingpiece 26 which is pivotally journaled at one end to the casing 24 andplaced at the central part on the pendulum. As the front end of theswing piece 26 approaches the external teeth 16 of the synchrogear 15,the swing piece 26 is engageable with the external teeth 16 by swinging.

When a high level of acceleration is experienced, such as in anaccident, sudden braking, etc., the pendulum 25 is swung to elevate theswing piece 26 and to allow it to swing whereby its front end is engagedwith the external teeth 16 of the synchrogear 15 to stop its rotation.This acceleration sensing device 23 is not specifically limited in itsstructure. In actual use, anyone can select a suitable one from theknown acceleration sensing devices.

A casing 27 covers all the emergency locking mechanism comprising theacceleration sensing device 23 equipped outside the side plate 3, theswing member 9, the synchrogear 15, the balance weight 19, the stopper20, etc. and is fixed to the side plate 3. The guide drum 4' functionsas a reel for a webbing W. The front end of the webbing to be wound onthe guide drum 4' forms a closed loop around a pin 31 and is insertedinto the spindle case 4" through a slit and is thereby fixed to theguide drum 4'.

The operation of the emergency locking retractor for seat belts will nowbe explained in detail.

FIG. 4 shows the emergency locking mechanism in a normal state of theemergency locking retractor shown in FIG. 1. In this state, the swingmember 9 is maintained in the disengaged position to the locking member5 by the resiliency of the spring means 22 so that the spindle 7, theswing member 9 and the synchrogear 15 can be rotated integrally to pullout or rewind the webbing W freely.

FIG. 5 shows the state of the emergency locking mechanism being actuatedwhen the body of a seat belt wearer is moved to strongly pull out of thewebbing W. In case the webbing W is strongly pulled out and the spindle7 is thus rotated rapidly, the rotation of the swing member 9 is delayedby inertia relative to the spindle 7 so that the insertion hole 13 forthe swing member 9 is contacted by the projections 8 of the spindle 7whereby the swing member 9 is swung downwardly in the drawing againstthe resiliency of the spring means 22 to permit engagement of thesupporting tooth 11 with the internal teeth 6. When the spindle 7 isrotated further in this state, the swing member 9 is then rotated in thecounterclockwise direction with the supporting tooth 11 functioning as afulcrum whereby the engaging teeth 10 are engaged with the internalteeth 6 to lock the retractor as shown in the drawing.

FIG. 6 shows the state of the emergency locking mechanism being actuatedby the operation of the acceleration sensing device 23. In the event astrong acceleration is added to the emergency locking retractor for seatbelts by any accident, sudden braking, etc., the pendulum 25 in theacceleration sensing device 23 is swung to elevate the swing piece 26for initiation of the acceleration sensing device 23 whereby the tip ofthe swing piece 26 is engaged with the internal teeth 16 of thesynchrogear 15 to stop its rotation.

In this state, a tension force is exerted to the webbing W and thespindle 7 is rotated in the counterclockwise direction in the drawing.In this case, the swing member 9 wherein the projection 14 has beeninserted into the guide hole 18 of the synchrogear 15 cannot be rotatedtogether with the spindle 7 whereby the insertion hole 13 is contactedby the projections 8 of the spindle 7 and the projection 14 is slidablymoved along the guide hole 18 with the result that the swing member 9 isswung downward in the drawing to permit engagement of the supportingtooth 11 with the internal teeth 6 of the locking member 9. The swingmember 9 is further swung, with the engaged point of the supportingtooth 11 and the internal teeth 6 functioning as a fulcrum, in thecounterclockwise direction in the drawing against the resiliency of thespring means 22 whereby the engaging teeth 10 are engaged with theinternal teeth 6 to lock the retractor as shown in the drawing.

In case of FIGS. 5 and 6 wherein the engaging teeth 10 of the swingmember 9 are engaged with the internal teeth 6 of the locking member 5,the rotation of the spindle 7 is stopped in each case to make itimpossible to pull out the webbing from the retractor.

In the retractors of this type, the winding shaft 4 is often disposedhorizontally in the usual cases. Thus, the emergency locking device isdisposed vertically and, in the case of the retractor of the presentinvention, a force in the downward direction is exerted on the swingmember 9 by its own weight. In case the webbing W is suddenly pulledout, therefore, the supporting tooth 11 of the swing member 9 isrelatively easily engaged by its own weight with the internal teeth 6 tofacilitate locking of the retractor when the supporting tooth 11 is inthe lower position. In case the supporting tooth 11 is in the upperposition, however, locking of the retractor becomes relatively difficultbecause the swing member 9 has to be biassed against its own weight. Incase of the emergency locking retractor of the present invention forseat belts wherein the synchrogear 15 is provided with the balanceweight 19, however, the balance weight 19 is positioned to left sidewhen the supporting tooth 11 is in the lower position so that a rotationforce in the direction of pulling out the webbing is exerted to thesynchrogear 15 by the self-weight of the balance weight 19. Accordingly,the guide hole 18 pushes the projection 14 lest the swing member 9should be delayed in rotation from the spindle 7 whereby locking of theretractor by the engagement of the supporting tooth 11 with the internalteeth 6 is prevented.

On the contrary, when the supporting tooth 11 is positioned in the upperposition, the balance weight 19 is positioned at the right side in thedrawing so that a rotation force in the direction of winding the webbingis exerted to the synchrogear 15. Accordingly, the rotation of thesynchrogear 15 tends to delay whereby it functions similarly to the casewherein the rotation of the synchrogear 15 is inhibited by the action ofthe acceleration sensing device 23 so that swing of the swing member 9is promoted to engage the supporting tooth 11 with the internal teeth 6.Thus, the retractor can function at all times under the same conditionirrespective of the position of the supporting tooth 11.

FIG. 7 shows the effect of the emergency locking retractor of thepresent invention for seat belts in such case that the engaging teeth 10can be engaged with the internal teeth 6 even if the supporting tooth 11is not correctly engaged with the inner teeth 6. In the retractor of thepresent invention, the locking mechanism proceeds in such manner thatthe supporting tooth 11 of the swing member 9 is initially engaged withthe internal teeth 6 of the locking member 5 and, successively to thisleading supporting tooth, the engaging teeth 10 of the swing member 9are then engaged with the internal teeth 6. As seen in the prior artemergency locking retractors for seat belts, however, there may be thecase wherein the supporting tooth 11 fails in some cases to engagecorrectly with the internal teeth 6, and the top of the supporting tooth11 abuts against the top of any one of the internal teeth 6. In theretractor of the present invention, the swing member 9 is rotated insuch case, with the abutting point between the supporting tooth 11 andthe internal tooth 6 functioning as a fulcrum, in the counterclockwisedirection. In this case, the engaging teeth 10 are correctly engagedwith the internal teeth 6 to lock the retractor as shown in FIG. 7.

In case the swing member 9 is further engaged by the spindle 7 to effectrotation in such state, the engaging teeth 10 may be disengaged from theinternal teeth 6. In the retractor of the present invention wherein theextending portion 12 is formed adjacent to the engaging teeth 10,however, the extending portion 12 abuts against the internal teeth 6 tosuppport them so that any excessive rotation of the swing member 9 tocause disengagement of the engaging teeth 10 is prevented.

In the prior art emergency locking retractors, there may be a danger ofdisengagement of the engaging teeth 10 from the internal teeth 6 whenthe retractor is actuated to create a strong belt tension which causestemporary elastic deformation of the housing 1 and the winding shaft 4whereupon the swing member 9 moves upward, as shown in FIGS. 5, 6 and 7.In an example of the retractor of the present invention as shown in FIG.1, the projections 8 formed at the tip of the spindle 7 are alwayspositioned above the surface of the swing member 9 and are engaged withthe upper surface of the swing member 9 at the time of emergency lockingthereby preventing the upward movement of the swing member 9. In theretractor of the present invention, a reinforcing plate 8' is mounted toa journal-supporting part of a side of the winding shaft 4 where theemergency locking mechanism is positioned, so that the winding shaft 4is less deformed even if the spindle case 4" is made of a syntheticresin. In the emergency locking retractor of the present invention forseat belts, the swing member 9 is first swung in the direction of theshorter edges of the spindle 7 as described above to cause engagement orcontact of the supporting tooth 11 with the internal teeth 6 in case ofemergency, and thereafter the swing member 9 is rotated around the pointof such engagement or contact as a fulcrum to cause engagement of theengaging teeth 10 with the internal teeth 6. It is assured thereforethat the engaging teeth 10 are engaged with the internal teeth 6 to lockthe retractor thereby entirely preventing the webbing from being pulledout, irrespective of the location the spindle 7 relative to the lockingmember 5 have. The operation is done very safely and with certainty. Theretractor can be maintained in a locked state with certainty since theupward movement of the swing member 9 can be prevented, as describedabove, by the projections 8 of the spindle 7 even when the tension forceof the seat belt becomes stronger in case of locking. Moreover, the loadcapacity of the retractor in case of the spindle 7 being positionedrectangularly to the direction of load can be improved significantly asthe reinforcing plate 8' prevents any deformation of the winding shaft4. As the shape of the insertion hole 13 in the swing member 9 is simpleand the function of the insertion hole is only to swing the swing member9 in case of being engaged and moved by the spindle 7, any speciallyhigh level of precision is not required for the manufacture of the swingmember, thus making this economically advantageous. As the balanceweight 19 eliminates the influence of the self-weight of the swingmember 9, the condition for locking the retractor is not influenced bythe location of the swing member 9. The retractor is operated alwaysunder a definite condition and is very safe in this respect.

FIG. 8 is a side sectional view showing another example of the emergencylocking retractor of the present invention for seat belts. In thisexample, two projections 14a and 14b are formed in the swing member 9and are inserted into two guide holes 18a and 18b formed in thesynchrogear 15 which is slidably movable with the winding shaft 4. Thestopper 20 is omitted and the spring means 22 is placed between theprojection 14a and a projection 28 formed in the synchrogear 15. Theprojection 14a is positioned in the neighborhood of the engaging teeth10 while the guide hole 18a into which the projection 14a is to beinserted is somewhat elongated in the peripheral direction of thesynchrogear 15 so that the engaging teeth 10 may be engaged with theinternal teeth 6 by sliding the projection 14a along the guide hole 18a.The other projection 14b is positioned in the neighborhood of thesupporting tooth 11 while the guide hole 18b is elongated in the radialdirection of the synchrogear 15.

FIG. 9 is an illustrative drawing showing the locked state of theretractor shown in FIG. 8. When the webbing is strongly pulled out andthe rotation of the swing member 9 is delayed or the swing piece 26 isengaged with the synchrogear 15 to stop the rotation of the synchrogear15, the insertion hole 13 is contacted by the spindle 7 whereby theprojection 14b is slid along the guide hole 18b to swing the swingmember 9 downward for engaging the supporting tooth 11 with the internalteeth 6. The swing member 9 is further swung in the counterclockwisedirection around the engaged position of the supporting tooth 11 and theinternal teeth 6 as a fulcrum whereby the projection 14a is slided alongthe guide hole 18a against the resiliency of the spring means 22 topermit engagement of the engaging teeth 10 with the internal teeth 6.Even when the top of the supporting tooth 11 is contacted with the topof an internal tooth 6, the operation proceeds in the same manner asshown in FIG. 7 whereby the engaging teeth 10 are engaged with theinternal teeth 6.

The emergency locking retractor of the present invention for seat beltshaving an improved emergency locking mechanism is actuated withcertainty in any of the cases and is lightweight and simple instructure. Further, the retractor is easily manufactured and succeeds inovercoming all the drawbacks of the similar prior art retractors. Thus,the retractor is especially useful in the industrial field oftransportation including motor vehicles.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

We claim:
 1. An emergency locking retractor for seat belts comprising:ahousing; a winding shaft located in said housing; a spindle integrallyprovided with said winding shaft, said spindle having substantiallyrectangular ends with opposing longer edges extending in a firstdirection and opposing shorter edges extending in a second direction; aswing member for receiving a portion of said spindle, said swing memberhaving engaging teeth and a supporting tooth on the outer peripherythereof, said engaging teeth being positioned on a side of said outerperiphery in the first direction, said supporting tooth being positionedon a side of said outer periphery in the second direction, said swingmember being capable of freely swinging against said spindle by movingin said first direction, said swing member further being capable offreely swinging against said spindle by moving in said second direction;a lock member fixed to said housing and having internal teeth engageablewith said engaging teeth and said supporting tooth of said swing member;a synchrogear having external teeth and being frictionally movable withsaid spindle and rotatable against said spindle by inertia to engage thesupporting tooth of the swing member with the internal teeth of the lockmember; an acceleration sensing device for engaging with the externalteeth of the synchrogear; and spring means for biasing at all times saidengaging teeth and said supporting tooth in a direction of disengagementfrom said lock member.
 2. The emergency locking retractor for seat beltsaccording to claim 1, wherein the swing member is provided with anextending portion adjacent to the engaging teeth.
 3. The emergencylocking retractor for seat belts according to claim 1, wherein thesynchrogear has been fixed with a balance weight to compensate fordeviations of the center of gravity of the swing member to the rotationcenter of the winding shaft.
 4. The emergency locking retractor for seatbelts according to claim 1, wherein one end of the spindle extend in thedirection of the longer edges to form projections which are positionedabove the surface of the swing member to prevent any upward movement ofthe swing member in case of locking.
 5. The emergency locking retractorfor seat belts according to claim 1, wherein one end of the windingshaft in which the lock member is positioned is provided with areinforcing plate.